EP2498679B1 - Systems and devices for evaluating the integrity of a uterine cavity - Google Patents

Description

CROSS-REFERENCES TO RELATED APPLICATIONS
• The present application claims priority ofU.S. Patent Application No.12/616,318 (Attorney Docket No. 027962-000300US), filed November 11, 2009, andU.S. Patent Application No. 12/616,343 (Attorney Docket No. 027962-000400US), filed November 11, 2009.
BACKGROUND1. Field of the Invention.
• The present invention relates to electrosurgical systems for global endometrial ablation in a treatment of menorrhagia. More particularly, the present invention relates to applying radiofrequency current to endometrial tissue by means of capacitively coupling the current through an expandable, thin-wall dielectric member enclosing an ionized gas.
• A variety of devices have been developed or proposed for endometrial ablation. Of relevance to the present invention, a variety of radiofrequency ablation devices have been proposed including solid electrodes, balloon electrodes, metalized fabric electrodes, and the like. While often effective, many of the prior electrode designs have suffered from one or more deficiencies, such as relatively slow treatment times, incomplete treatments, non-uniform ablation depths, and risk of injury to adjacent organs.
• For these reasons, it would be desirable to provide systems and methods that allow for endometrial ablation using radiofrequency current which is rapid, provides for controlled ablation depth and which reduce the risk of injury to adjacent organs. At least some of these objectives will be met by the invention described herein.
2. Description of the Background Art.
• U.S. Patent Nos. 5,769,880;6,296,639;6,663,626; and6,813,520 describe intrauterine ablation devices formed from a permeable mesh defining electrodes for the application of radiofrequency energy to ablate uterine tissue.U.S. Patent No. 4,979,948 describes a balloon filled with an electrolyte solution for applying radiofrequency current to a mucosal layer via capacitive coupling.US 2008/097425, having common inventorship with the present application, describes delivering a pressurized flow of a liquid medium which carries a radiofrequency current to tissue, where the liquid is ignited into a plasma as it passes through flow orifices.US 5,891,134 describes a radiofrequency heater within an enclosed balloon.US 6,041,260 describes radiofrequency electrodes distributed over the exterior surface of a balloon which is inflated in a body cavity to be treated.US 7,371,231 andUS 2009/054892 describe a conductive balloon having an exterior surface which acts as an electrode for performing endometrial ablation.US 5,191,883 describes bipolar heating of a medium within a balloon for thermal ablation.US 6,736,811 andUS 5,925,038 show an inflatable conductive electrode.
• US2008/0167644 describes a device for verifying occlusion of a fallopian tube. Thedevice includes an elongate gas delivery member having a lumen disposed therein. The elongate gas delivery member is adapted for sealing engagement with the subject's uterus. The device includes a pressurized insufflation gas source coupled to the elongate gas delivery member. The device may include a pressure sensor or gauge to measure intra-uterine pressure to verify occlusion of the fallopian tube or the flow rate of insufflation gas into the uterus may be measured using a flow meter to verify occlusion of the fallopian tube.
• US2005/0143728 describes a system and method for detecting perforations in a body cavity such as a uterus. In the described method, a fluid (liquid or gas) is delivered into the body cavity to slightly pressurize the cavity and a pressure sensing system monitors the pressure within the cavity for a predetermined test period. If cavity pressure is not substantially sustained during the test period, the physician is alerted to further assess the cavity for perforations before initiating treatment within the cavity. A medical system such as an RF ablation system may be provided with this perforation detection functionality.
BRIEF SUMMARY
• The present invention is set out in the appended claims. Described herein are integrity of a uterine cavity. The uterine cavity may be perforated or otherwise damaged by the transcervical introduction of probes and instruments into the uterine cavity. If the uterine wall is perforated, it would be preferable to defer any ablation treatment until the uterine wall is healed. A described method comprises introducing transcervically a probe into a patient's uterine cavity, providing a flow of a fluid (e.g., CO₂) through the probe into the uterine cavity and monitoring the rate of the flow to characterize the uterine cavity as perforated or non-perforated based on a change in the flow rate. If the flow rate drops to zero or close to zero, this indicates that the uterine cavity is intact and not perforated. If the flow rate does not drop to zero or close to zero, this indicates that a fluid flow is leaking through a perforation in the uterine cavity into the uterine cavity or escaping around an occlusion balloon that occludes the cervical canal.
• In embodiments, a system for characterizing a patient uterus is provided, comprising a source of a pressurized flow of a fluid; a lumen connected to the source and configured to deliver the fluid from the source a uterine cavity of a patient; a flow sensor for monitoring the flow of the fluid from the lumen into the uterine cavity; and a controller operatively coupled to the flow meter configured to characterize the uterine cavity as at least one of perforated or non-perforated based on a change in the flow.
• The controller may, for example, generate a signal if the flow does not drop below a predetermined level to thus characterize the uterine cavity as perforated. The signal may be at least one of visual, aural and tactile.
• The controller in embodiments generates a signal if the flow drops below a predetermined level to thus characterize the uterine cavity as non-perforated. The signal may be at least one of visual, aural and tactile.
• In embodiments, a probe is included that is configured for transcervical introduction into a patient's uterine cavity, and the lumen is mounted to the probe. An expandable member may be carried by the probe for expanding in the cervical canal. The expandable member may be, for example, a balloon.
• The probe may include a working end having an energy-delivery surface for ablating uterine cavity tissue. In embodiments, the energy-delivery surface is configured to deliver RF energy to the tissue. The energy-delivery surface may include at least one electrode coupled to a RF generator. In embodiments, the controller is configured to disable activation of the energy-delivery surface if the uterine cavity is characterized as perforated. An override mechanism may be provided to override the disabling mechanism.
• The controller may also or alternatively be configured to enable activation of the energy-delivery surface if the uterine cavity is characterized as non-perforated. In embodiments, the controller is configured to automatically activate the energy delivery surface if the uterine cavity is characterized as non-perforated.
• In embodiments, the controller is configured to characterize the uterine cavity as at least one of perforated or non-perforated based on a change in a rate of the flow.
BRIEF DESCRIPTION OF THE DRAWINGS
• In order to better understand the invention and to see how it may be carried out in practice, some preferred embodiments are next described, by way of non-limiting examples only, with reference to the accompanying drawings, in which like reference characters denote corresponding features consistently throughout similar embodiments in the attached drawings.
• FIG. 1 is a perspective view of an ablation system including a hand-held electrosurgical device for endometrial ablation, RF power source, gas source and controller.
• FIG. 2 is a view of the hand-held electrosurgical device ofFIG. 1 with a deployed, expanded thin-wall dielectric structure.
• FIG. 3 is a block diagram of components of one electrosurgical system.
• FIG. 4 s a block diagram of the gas flow components of the electrosurgical system ofFIG. 1.
• FIG. 5 is an enlarged perspective view of the expanded thin-wall dielectric structure, showing an expandable-collapsible frame with the thin dielectric wall in phantom view.
• FIG. 6 is a partial sectional view of the expanded thin-wall dielectric structure ofFIG. 5 showing (i) translatable members of the expandable-collapsible frame a that move the structure between collapsed and (ii) gas inflow and outflow lumens.
• FIG. 7 is a sectional view of an introducer sleeve showing various lumens of the introducer sleeve taken along line 7-7 ofFIG. 6.
• FIG. 8A is an enlarged schematic view of an aspect of a method for evaluating the integrity of a uterus cavity, illustrating the step introducing an introducer sleeve into a patient's uterus.
• FIG. 8B is a schematic view of a subsequent step of retracting the introducer sleeve to expose a collapsed thin-wall dielectric structure and internal frame in the uterine cavity.
• FIG. 8C is a schematic view of subsequent steps of the method, including, (i) actuating the internal frame to move the a collapsed thin-wall dielectric structure to an expanded configuration, (ii) inflating a cervical-sealing balloon carried on the introducer sleeve, and (iii) actuating gas flows and applying RF energy to contemporaneously ionize the gas in the interior chamber and cause capacitive coupling of current through the thin-wall dielectric structure to cause ohmic heating in the engaged tissue indicated by current flow paths.
• FIG. 8D is a schematic view of, subsequent steps of the method, including: (i) advancing the introducer sleeve over the thin-wall dielectric structure to collapse it into an interior bore shown in phantom view, and (ii) withdrawing the introducer sleeve and dielectric structure from the uterine cavity.
• FIG. 9 is a cut-away perspective view of an alternative expanded thin-wall dielectric structure similar to that ofFIGS. 5 and6 show an alternative electrode configuration.
• FIG. 10 is an enlarged cut-away view of a portion of the expanded thin-wall dielectric structure ofFIG. 9 showing the electrode configuration.
• FIG. 11 is a schematic view of a patient uterus depicting a method for evaluating the integrity of a uterus cavity, including providing a flow of a fluid media into the uterine cavity and monitoring the flow rate to characterize the patient's uterine cavity as intact and non-perforated.Figure 11 discloses an embodiment of the invention.
• FIG. 12 is a perspective view of the ablation device ofFIGS. 1-2 with a subsystem for checking the integrity of a uterine cavity.
• FIG. 13 represents a block diagram of a subsystem for providing and monitoring a fluid flow into the patient's uterine cavity.
• FIG. 14 represents a diagram indicating the steps of an algorithm for providing and monitoring a fluid flow into the patient's uterine cavity.
DETAILED DESCRIPTION
• In general, an electrosurgical ablation system is described herein that comprises an elongated introducer member for accessing a patient's uterine cavity with a working end that deploys an expandable thin-wall dielectric structure containing an electrically non-conductive gas as a dielectric. In one embodiment, an interior chamber of the thin-wall dielectric structure contains a circulating neutral gas such as argon. An RF power source provides current that is coupled to the neutral gas flow by a first polarity electrode disposed within the interior chamber and a second polarity electrode at an exterior of the working end. The gas flow, which is converted to a conductive plasma by an electrode arrangement, functions as a switching mechanism that permits current flow to engaged endometrial tissue only when the voltage across the combination of the gas, the thin-wall dielectric structure and the engaged tissue reaches a threshold that causes capacitive coupling across the thin-wall dielectric material. By capacitively coupling current to tissue in this manner, the system provides a substantially uniform tissue effect within all tissue in contact with the expanded dielectric structure. Further, the neutral gas may be created contemporaneously with the capacitive coupling of current to tissue.
• In general, this disclosure may use the terms "plasma," "conductive gas" and "ionized gas" interchangeably. A plasma consists of a state of matter in which electrons in a neutral gas are stripped or "ionized" from their molecules or atoms. Such plasmas can be formed by application of an electric field or by high temperatures. In a neutral gas, electrical conductivity is non-existent or very low. Neutral gases act as a dielectric or insulator until the electric field reaches a breakdown value, freeing the electrons from the atoms in an avalanche process thus forming a plasma. Such a plasma provides mobile electrons and positive ions, and acts as a conductor which supports electric currents and can form spark or arc. Due to their lower mass, the electrons in a plasma accelerate more quickly in response to an electric field than the heavier positive ions, and hence carry the bulk of the current.
• FIG. 1 depicts one embodiment of anelectrosurgical ablation system 100 configured for endometrial ablation. Thesystem 100 includes a hand-heldapparatus 105 with aproximal handle 106 shaped for grasping with a human hand that is coupled to anelongated introducer sleeve 110 havingaxis 111 that extends to adistal end 112. Theintroducer sleeve 110 can be fabricated of a thin-wall plastic, composite, ceramic or metal in a round or oval cross-section having a diameter or major axis ranging from about 4 mm to 8 mm in at least a distal portion of the sleeve that accesses the uterine cavity. Thehandle 106 is fabricated of an electrically insulative material such as a molded plastic with a pistol-grip having first and second portions, 114a and 114b, that can be squeezed toward one another to translate an elongatedtranslatable sleeve 115 which is housed in abore 120 in theelongated introducer sleeve 110. By actuating the first and second handle portions, 114a and 114b, a workingend 122 can be deployed from a first retracted position (FIG. 1) in the distal portion ofbore 120 inintroducer sleeve 110 to an extended position as shown inFIG. 2. InFIG. 2, it can be seen that the first and second handle portions, 114a and 114b, are in a second actuated position with the workingend 122 deployed from thebore 120 inintroducer sleeve 110.
• FIGS. 2 and3 shows thatablation system 100 includes anRF energy source 130A andRF controller 130B in acontrol unit 135. TheRF energy source 130A is connected to the hand-helddevice 105 by aflexible conduit 136 with a plug-inconnector 137 configured with a gas inflow channel, a gas outflow channel, and first and second electrical leads for connecting to receivingconnector 138 in thecontrol unit 135. Thecontrol unit 135, as will be described further below inFIGS. 3 and4, further comprises a neutralgas inflow source 140A,gas flow controller 140B and optional vacuum ornegative pressure source 145 to provide controlled gas inflows and gas outflows to and from the workingend 122. Thecontrol unit 135 further includes aballoon inflation source 148 for inflating anexpandable sealing balloon 225 carried onintroducer sleeve 110 as described further below.
• Referring toFIG .3 the workingend 122 includes a flexible, thin-wall member orstructure 150 of a dielectric material that when expanded has a triangular shape configured for contacting the patient's endometrial lining that is targeted for ablation. In one embodiment as shown inFIGS. 2,5 and6, thedielectric structure 150 comprises a thin-wall material such as silicone with a fluid-tightinterior chamber 152.
• In an embodiment, an expandable-collapsible frame assembly 155 is disposed in the interior chamber. Alternatively, the dielectric structure may be expanded by a neutral gas without a frame, but using a frame offers a number of advantages. First, the uterine cavity is flattened with the opposing walls in contact with one another. Expanding a balloon-type member may cause undesirable pain or spasms. For this reason, a flat structure that is expanded by a frame is better suited for deployment in the uterine cavity. Second, in embodiments herein, the neutral gas is converted to a conductive plasma at a very low pressure controlled by gas inflows and gas outflows--so that any pressurization of a balloon-type member with the neutral gas may exceed a desired pressure range and would require complex controls of gas inflows and gas outflows. Third, as described below, the frame provides an electrode for contact with the neutral gas in theinterior chamber 152 of thedielectric structure 150, and theframe 155 extends into all regions of the interior chamber to insure electrode exposure to all regions of the neutral gas and plasma. Theframe 155 can be constructed of any flexible material with at least portions of the frame functioning as spring elements to move the thin-wall structure 150 from a collapsed configuration (FIG. 1) to an expanded, deployed configuration (FIG. 2) in a patient's uterine cavity. In one embodiment, theframe 155 comprisesstainless steel elements 158a, 158b and 160a and 160b that function akin to leaf springs. The frame can be a stainless steel such as 316 SS, 17A SS, 420 SS, 440 SS or the frame can be a NiTi material. The frame preferably extends along a single plane, yet remains thin transverse to the plane, so that the frame may expand into the uterine cavity. The frame elements can have a thickness ranging from about 0.005"to 0.025". As can be seen inFIGS. 5 and6, the proximal ends 162a and 162b ofspring elements 158a, 158b are fixed (e.g., by welds 164) to thedistal end 165 ofsleeve member 115. The proximal ends 166a and 166b ofspring elements 160a, 160b are welded todistal portion 168 of a secondarytranslatable sleeve 170 that can be extended frombore 175 intranslatable sleeve 115. The secondarytranslatable sleeve 170 is dimensioned for a loose fit inbore 175 to allow gas flows withinbore 175.FIGS. 5 and6 further illustrate the distal ends 176a and 176b ofspring elements 158a, 158b are welded todistal ends 178a and 178b ofspring elements 160a and 160b to thus provide aframe 155 that can be moved from a linear shape (seeFIG.1) to an expanded triangular shape (FIGS. 5 and6).
• As will be described further below, thebore 175 insleeve 115 and bore 180 in secondarytranslatable sleeve 170 function as gas outflow and gas inflow lumens, respectively. It should be appreciated that the gas inflow lumen can comprise any single lumen or plurality of lumens in eithersleeve 115 orsleeve 170 or another sleeve, or other parts of theframe 155 or the at least one gas flow lumen can be formed into a wall ofdielectric structure 150. InFIGS. 5,6 and7 it can be seen that gas inflows are provided throughbore 180 insleeve 170, and gas outflows are provided inbore 175 ofsleeve 115. However, the inflows and outflows can be also be reversed betweenbores 175 and 180 of the various sleeves.FIGS. 5 and6 further show that arounded bumper element 185 is provided at the distal end ofsleeve 170 to insure that no sharp edges of the distal end ofsleeve 170 can contact the inside of the thindielectric wall 150. In one embodiment, thebumper element 185 is silicone, but it could also comprise a rounded metal element.FIGS. 5 and6 also show that a plurality ofgas inflow ports 188 can be provided along a length of insleeve 170 inchamber 152, as well as aport 190 in the distal end ofsleeve 170 andbumper element 185. The sectional view ofFIG. 7 also shows the gas flow passageways within the interior ofintroducer sleeve 110.
• It can be understood fromFIGS. 1,2,5 and6 that actuation of first and second handle portions, 114a and 114b, (i) initially causes movement of the assembly ofsleeves 115 and 170 relative to bore 120 ofintroducer sleeve 110, and (ii) secondarily causes extension ofsleeve 170 frombore 175 insleeve 115 to expand theframe 155 into the triangular shape ofFIG. 5. The dimensions of the triangular shape are suited for a patient uterine cavity, and for example can have an axial length A ranging from 4 to 10 cm and a maximum width B at the distal end ranging from about 2 to 5 cm. In one embodiment, the thickness C of the thin-wall structure 150 can be from 1 to 4 mm as determined by the dimensions ofspring elements 158a, 158b, 160a and 160b offrame assembly 155. It should be appreciated that theframe assembly 155 can comprise round wire elements, flat spring elements, of any suitable metal or polymer that can provide opening forces to move thin-wall structure 150 from a collapsed configuration to an expanded configuration within the patient uterus. Alternatively, some elements of theframe 155 can be spring elements and some elements can be flexible without inherent spring characteristics.
• As will be described below, the working end embodiment ofFIGS. 2,5 and6 has a thin-wall structure 150 that is formed of a dielectric material such as silicone that permits capacitive coupling of current to engaged tissue while theframe assembly 155 provides structural support to position the thin-wall structure 150 against tissue. Further, gas inflows into theinterior chamber 152 of the thin-wall structure can assist in supporting the dielectric wall so as to contact endometrial tissue. The dielectric thin-wall structure 150 can be free from fixation to theframe assembly 155, or can be bonded to an outward-facing portion or portions offrame elements 158a and 158b. Theproximal end 182 of thin-wall structure 150 is bonded to the exterior of the distal end ofsleeve 115 to thus provide a sealed, fluid-tight interior chamber 152 (FIG. 5).
• In one embodiment, thegas inflow source 140A comprises one or more compressed gas cartridges that communicate withflexible conduit 136 through plug-inconnector 137 and receivingconnector 138 in the control unit 135 (FIGS. 1-2). As can be seen inFIGS. 5-6, the gas inflows fromsource 140A flow throughbore 180 insleeve 170 to openterminations 188 and 190 therein to flow intointerior chamber 152. Avacuum source 145 is connected throughconduit 136 andconnector 137 to allow circulation of gas flow through theinterior chamber 152 of the thin-wall dielectric structure 150. InFIGS. 5 and6, it can be seen that gas outflows communicate withvacuum source 145 throughopen end 200 ofbore 175 insleeve 115. Referring toFIG. 5, it can be seen thatframe elements 158a and 158b are configured with a plurality ofapertures 202 to allow for gas flows through all interior portions of the frame elements, and thus gas inflows fromopen terminations 188, 190 inbore 180 are free to circulated throughinterior chamber 152 to return to an outflow path throughopen end 200 ofbore 175 ofsleeve 115. As will be described below (seeFIGS. 3-4), thegas inflow source 140A is connected to a gas flow orcirculation controller 140B which controls apressure regulator 205 and also controlsvacuum source 145 which is adapted for assisting in circulation of the gas. It should be appreciated that the frame elements can be configured with apertures, notched edges or any other configurations that allow for effective circulation of a gas throughinterior chamber 152 of the thin-wall structure 150 between the inflow and outflow passageways.
• Now turning to the electrosurgical aspects of the disclosure,FIGS. 5 and6 illustrate opposing polarity electrodes of thesystem 100 that are configured to convert a flow of neutral gas inchamber 152 into a plasma 208 (FIG. 6) and to allow capacitive coupling of current through awall 210 of the thin-wall dielectric structure 150 to endometrial tissue in contact with thewall 210. The electrosurgical methods of capacitively coupling RF current across aplasma 208 anddielectric wall 210 are described inUS Patent Application 12/541,043; filed August 13, 2009 (Atty. Docket No. 027980-000110US) andU.S. Application No. 12/541,050 (Atty. Docket No. 027980-000120US). InFIGS. 5 and6, thefirst polarity electrode 215 is withininterior chamber 152 to contact the neutral gas flow and comprises theframe assembly 155 that is fabricated of an electrically conductive stainless steel. In another embodiment, the first polarity electrode can be any element disposed within theinterior chamber 152, or extendable intointerior chamber 152. Thefirst polarity electrode 215 is electrically coupled tosleeves 115 and 170 which extends through theintroducer sleeve 110 to handle 106 andconduit 136 and is connected to a first pole of the RFsource energy source 130A andcontroller 130B. Asecond polarity electrode 220 is external of theinternal chamber 152 and in one embodiment the electrode is spaced apart fromwall 210 of the thin-wall dielectric structure 150. In one embodiment as depicted inFIGS. 5 and6, thesecond polarity electrode 220 comprises a surface element of anexpandable balloon member 225 carried byintroducer sleeve 110. Thesecond polarity electrode 220 is coupled by a lead (not shown) that extends through theintroducer sleeve 110 andconduit 136 to a second pole of theRF source 130A. It should be appreciated thatsecond polarity electrode 220 can be positioned onsleeve 110 or can be attached to surface portions of the expandable thin-wall dielectric structure 150, as will be described below, to provide suitable contact with body tissue to allow the electrosurgical ablation. Thesecond polarity electrode 220 can comprise a thin conductive metallic film, thin metal wires, a conductive flexible polymer or a polymeric positive temperature coefficient material. In one embodiment depicted inFIGS. 5 and6, theexpandable member 225 comprises a thin-wall compliant balloon having a length of about 1 cm to 6 cm that can be expanded to seal the cervical canal. Theballoon 225 can be inflated with a gas or liquid by anyinflation source 148, and can comprise a syringe mechanism controlled manually or bycontrol unit 135. Theballoon inflation source 148 is in fluid communication with aninflation lumen 228 inintroducer sleeve 110 that extends to an inflation chamber of balloon 225 (seeFIG. 7).
• Referring back toFIG. 1, thecontrol unit 135 can include adisplay 230 and touch screen orother controls 232 for setting and controlling operational parameters such as treatment time intervals, treatment algorithms, gas flows, power levels and the like. Suitable gases for use in the system include argon, other noble gases and mixtures thereof. In one embodiment, afootswitch 235 is coupled to thecontrol unit 135 for actuating the system.
• The box diagrams ofFIGS. 3 and4 schematically depict thesystem 100, subsystems and components that are configured for an endometrial ablation system. In the box diagram ofFIG. 3, it can be seen thatRF energy source 130A and circuitry is controlled by acontroller 130B. The system can include feedback control systems that include signals relating to operating parameters of the plasma ininterior chamber 152 of thedielectric structure 150. For example, feedback signals can be provided from at least onetemperature sensor 240 in theinterior chamber 152 of thedielectric structure 150, from a pressure sensor within, or in communication, withinterior chamber 152, and/or from a gas flow rate sensor in an inflow or outflow channel of the system.FIG. 4 is a schematic block diagram of the flow control components relating to the flow of gas media through thesystem 100 and hand-helddevice 105. It can be seen that apressurized gas source 140A is linked to adownstream pressure regulator 205, an inflowproportional valve 246,flow meter 248 and normally closedsolenoid valve 250. Thevalve 250 is actuated by the system operator which then allows a flow of a neutral gas fromgas source 140A to circulate throughflexible conduit 136 and thedevice 105. The gas outflow side of the system includes a normallyopen solenoid valve 260, outflowproportional valve 262 and flowmeter 264 that communicate with vacuum pump orsource 145. The gas can be exhausted into the environment or into a containment system. A temperature sensor 270 (e.g., thermocouple) is shown inFIG. 4 that is configured for monitoring the temperature of outflow gases.FIG. 4 further depicts anoptional subsystem 275 which comprises avacuum source 280 andsolenoid valve 285 coupled to thecontroller 140B for suctioning steam from auterine cavity 302 at an exterior of thedielectric structure 150 during a treatment interval. As can be understood fromFIG. 4, the flow passageway from theuterine cavity 302 can be throughbore 120 in sleeve 110 (seeFIGS. 2,6 and7) or another lumen in a wall ofsleeve 110 can be provided.
• FIGS. 8A-8D schematically illustrate a method of the disclosure wherein (i) the thin-wall dielectric structure 150 is deployed within a patient uterus and (ii) RF current is applied to a contained neutral gas volume in theinterior chamber 152 to contemporaneously create aplasma 208 in the chamber and capacitively couple current through the thindielectric wall 210 to apply ablative energy to the endometrial lining to accomplish global endometrial ablation.
• More in particular,FIG. 8A illustrates apatient uterus 300 withuterine cavity 302 surrounded byendometrium 306 andmyometrium 310. The externalcervical os 312 is the opening of the cervix 314 into thevagina 316. The internal os or opening 320 is a region of the cervical canal that opens to theuterine cavity 302.FIG. 8A depicts a first step of a method of the disclosure wherein the physician has introduced a distal portion ofsleeve 110 into theuterine cavity 302. The physician gently can advance thesleeve 110 until its distal tip contacts thefundus 324 of the uterus. Prior to insertion of the device, the physician can optionally introduce a sounding instrument into the uterine cavity to determine uterine dimensions, for example from theinternal os 320 tofundus 324.
• FIG. 8B illustrates a subsequent step of a method of the disclosure wherein the physician begins to actuate the first and second handle portions, 114a and 114b, and theintroducer sleeve 110 retracts in the proximal direction to expose thecollapsed frame 155 and thin-wall structure 150 within theuterine cavity 302. Thesleeve 110 can be retracted to expose a selected axial length of thin-wall dielectric structure 150, which can be determined bymarkings 330 on sleeve 115 (seeFIG. 1) which indicate the axial travel ofsleeve 115 relative tosleeve 170 and thus directly related to the length of deployed thin-wall structure 150.FIG. 2 depicts thehandle portions 114a and 114b fully approximated thus deploying the thin-wall structure to its maximum length.
• FIG. 8C illustrates several subsequent steps of a method of the disclosure.FIG. 8C first depicts the physician continuing to actuate the first and second handle portions, 114a and 114b, which further actuates the frame 155 (seeFIGS. 5-6) to expand theframe 155 and thin-wall structure 150 to a deployed triangular shape to contact the patient'sendometrial lining 306. The physician can slightly rotate and move the expandingdielectric structure 150 back and forth as the structure is opened to insure it is opened to the desired extent. In performing this step, the physician can actuate handle portions, 114a and 114b, a selected degree which causes a select length of travel ofsleeve 170 relative tosleeve 115 which in turn opens theframe 155 to a selected degree. The selected actuation ofsleeve 170 relative tosleeve 115 also controls the length of dielectric structure deployed fromsleeve 110 into the uterine cavity. Thus, the thin-wall structure 150 can be deployed in the uterine cavity with a selected length, and the spring force of the elements offrame 155 will open thestructure 150 to a selected triangular shape to contact or engage theendometrium 306. In one embodiment, the expandable thin-wall structure 150 is urged toward and maintained in an open position by the spring force of elements of theframe 155. In the embodiment depicted inFIGS. 1 and2, thehandle 106 includes a locking mechanism with finger-actuatedsliders 332 on either side of the handle that engage a grip-lock element against a notch inhousing 333 coupled to introducer sleeve 110 (FIG. 2) to locksleeves 115 and 170 relative tointroducer sleeve 110 to maintain the thin-wall dielectric structure 150 in the selected open position.
• FIG. 8C further illustrates the physician expanding theexpandable balloon structure 225 frominflation source 148 to thus provide an elongated sealing member to seal thecervix 314 outward from theinternal os 320. Following deployment of the thin-wall structure 150 andballoon 225 in thecervix 314, thesystem 100 is ready for the application of RF energy to ablateendometrial tissue 306.FIG. 8C next depicts the actuation of thesystem 100, for example, by actuatingfootswitch 235, which commences a flow of neutral gas fromsource 140A into theinterior chamber 152 of the thin-wall dielectric structure 150. Contemporaneous with, or after a selected delay, the system's actuation delivers RF energy to the electrode arrangement which includes first polarity electrode 215 (+) offrame 155 and the second polarity electrode 220 (-) which is carried on the surface ofexpandable balloon member 225. The delivery of RF energy delivery will instantly convert the neutral gas ininterior chamber 152 intoconductive plasma 208 which in turn results in capacitive coupling of current through thedielectric wall 210 of the thin-wall structure 150 resulting in ohmic heating of the engaged tissue.FIG. 8C schematically illustrates the multiplicity of RFcurrent paths 350 between theplasma 208 and thesecond polarity electrode 220 through thedielectric wall 210. By this method, it has been found that ablation depths of three mm to six mm or more can be accomplished very rapidly, for example in 60 seconds to 120 seconds dependent upon the selected voltage and other operating parameters. In operation, the voltage at which the neutral gas inflow, such as argon, becomes conductive (i.e., converted in part into a plasma) is dependent upon a number of factors controlled by thecontrollers 130B and 140B, including the pressure of the neutral gas, the volume ofinterior chamber 152, the flow rate of the gas through thechamber 152, the distance betweenelectrode 210 and interior surfaces of thedielectric wall 210, the dielectric constant of thedielectric wall 210 and the selected voltage applied by the RF source 130, all of which can be optimized by experimentation. In one embodiment, the gas flow rate can be in the range of 5 ml/sec to 50 ml/sec. Thedielectric wall 210 can comprise a silicone material having a thickness ranging from a 0.005" to 0.015 and having a relative permittivity in the range of 3 to 4. The gas can be argon supplied in a pressurized cartridge which is commercially available. Pressure in theinterior chamber 152 ofdielectric structure 150 can be maintained between 14 psia and 15 psia with zero or negative differential pressure betweengas inflow source 140A and negative pressure orvacuum source 145. The controller is configured to maintain the pressure in interior chamber in a range that varies by less than 10% or less than 5% from a target pressure. TheRF power source 130A can have a frequency of 450 to 550 KHz, and electrical power can be provided within the range of 600Vrms to about 1200Vrms and about 0.2 Amps to 0.4 Amps and an effective power of 40W to 100W. In one method, thecontrol unit 135 can be programmed to delivery RF energy for a preselected time interval, for example, between 60 seconds and 120 seconds. One aspect of a treatment method consists of ablating endometrial tissue with RF energy to elevate endometrial tissue to a temperature greater than 45 degrees Celsius for a time interval sufficient to ablate tissue to a depth of at least 1 mm. Another aspect of the method of endometrial ablation of consists of applying radiofrequency energy to elevate endometrial tissue to a temperature greater than 45 degrees Celsius without damaging the myometrium.
• FIG. 8D illustrates a final step of the method wherein the physician deflates theexpandable balloon member 225 and then extendssleeve 110 distally by actuating thehandles 114a and 114b to collapseframe 155 and then retracting the assembly from theuterine cavity 302. Alternatively, the deployed workingend 122 as shown inFIG. 8C can be withdrawn in the proximal direction from the uterine cavity wherein theframe 155 and thin-wall structure 150 will collapse as it is pulled through the cervix.FIG. 8D shows the completed ablation with the ablated endometrial tissue indicated at 360.
• In another embodiment, the system can include an electrode arrangement in thehandle 106 or within the gas inflow channel to pre-ionize the neutral gas flow before it reaches theinterior chamber 152. For example, the gas inflow channel can be configured with axially or radially spaced apart opposing polarity electrodes configured to ionize the gas inflow. Such electrodes would be connected in separate circuitry to an RF source. The first and second electrodes 215 (+) and 220 (-) described above would operate as described above to provide the current that is capacitively coupled to tissue through the walls of thedielectric structure 150. In all other respects, the system and method would function as described above.
• Now turning toFIGS. 9 and10, analternate working end 122 with thin-wall dielectric structure 150 is shown. In this embodiment, the thin-wall dielectric structure 150 is similar to that ofFIGS. 5 and6 except that the second polarity electrode 220' that is exterior of theinternal chamber 152 is disposed on asurface portion 370 of the thin-wall dielectric structure 150. In this embodiment, the second polarity electrode 220' comprises a thin-film conductive material, such as gold, that is bonded to the exterior of thin-wall material 210 along twolateral sides 354 ofdielectric structure 150. It should be appreciated that the second polarity electrode can comprise one or more conductive elements disposed on the exterior ofwall material 210, and can extend axially, or transversely toaxis 111 and can be singular or multiple elements. In one embodiment shown in more detail inFIG. 10, the second polarity electrode 220' can be fixed on anotherlubricious layer 360, such as a polyimide film, for example KAPTON®. The polyimide tape extends about thelateral sides 354 of thedielectric structure 150 and provides protection to thewall 210 when it is advanced from or withdrawn intobore 120 insleeve 110. In operation, the RF delivery method using the embodiment ofFIGS. 9 and10 is the same as described above, with RF current being capacitively coupled from theplasma 208 through thewall 210 and endometrial tissue to the second polarity electrode 220' to cause the ablation.
• FIG. 9 further shows anoptional temperature sensor 390, such as a thermocouple, carried at an exterior of thedielectric structure 150. In one method of use, thecontrol unit 135 can acquire temperature feedback signals from at least onetemperature sensor 390 to modulate or terminate RF energy delivery, or to modulate gas flows within the system. Thecontrol unit 135 can acquire temperature feedback signals fromtemperature sensor 240 in interior chamber 152 (FIG. 6 to modulate or terminate RF energy delivery or to modulate gas flows within the system.
• In an embodiment of the invention,FIGS. 11-14 depict a system for evaluating the integrity of the uterine cavity which may be perforated or otherwise damaged by the transcervical introduction of probes and instruments into a uterine cavity. If the uterine wall is perforated, it would be preferable to defer any ablation treatment until the uterine wall is healed. A probe is introduced transcervically into a patient's uterine cavity, providing a flow of a fluid (e.g., CO2) through the probe into the uterine cavity and monitoring the rate of the flow to characterize the uterine cavity as perforated or non-perforated based on a change in the flow rate. If the flow rate drops to zero or close to zero, this indicates that the uterine cavity is intact and not perforated. If the flow rate does not drop to zero or close to zero, this indicates that a fluid flow is leaking through a perforation in theuterine cavity 302 into the uterine cavity or escaping around an occlusion balloon that occludes the cervical canal.
• InFIG. 11, it can be seen how a pressurizedfluid source 405 andcontroller 410 for controlling and monitoring flows is in fluid communication withlumen 120 of introducer sleeve 110 (seeFIG. 7). In one embodiment, the fluid source can be a pressurized cartridge containing CO2 or another biocompatible gas. InFIG. 12, it can be seen thatfluid source 405 communicates with aflexible conduit 412 that is connected to a "pig-tail"tubing connector 414 extending outward fromhandle 106 of the hand-held probe. A tubing in the interior ofhandle component 114a provides aflow passageway 415 to thelumen 120 in the introducer sleeve. In another embodiment, thefluid source 405 and flexible conduit 408 can be integrated intoconduit 136 ofFIG. 1.
• InFIG. 11, it can be seen that the flow of fluid is introduced into theuterine cavity 302 after theballoon 225 in the cervical canal has been inflated and after the working end anddielectric structure 150 has been expanded into its triangular shape to occupy the uterine cavity. Thus, the CO2 gas flows around the exterior surfaces of expandeddielectric structure 150 to fill the uterine cavity. Alternatively, the flow of CO2 can be provided after theballoon 225 in the cervical canal is inflated but before thedielectric structure 150 is expanded.
• FIG. 13 is a block diagram that schematically depicts the components ofsubsystem 420 that provides the flow of CO2 to and through the hand-heldprobe 105. It can be seen that pressurizedfluid source 405 communicates with adownstream pressure regulator 422, aproportional valve 424,flow meter 440, normally closedsolenoid valve 450 and one-way valve 452. Thevalve 450 upon actuation by the system operator allows a flow of CO2 gas fromsource 405 at a predetermined flow rate and pressure through the subsystem and into theuterine cavity 302.
• In one embodiment of the method of operation, the physician actuates the system and electronically opensvalve 450 which can provide a CO2 flow through the system. Thecontroller 410 monitors the flow meter orsensor 440 over an interval that can range from 1 second to 60 seconds, or 5 second to 30 seconds to determine the change in the rate of flow and/or a change in the rate of flow. In an embodiment, the flow sensor comprises a Honeywell AWM5000 Series Mass Airflow Sensor, for example Model AWM5101, that measure flows in units of mass flow. In one embodiment, the initial flow rate is between 0.05 slpm (standard liters per minute) and 2.0 slpm, or between 0.1 slpm and 0.2 slpm. Thecontroller 410 includes a microprocessor or programmable logic device that provides a feedback signal from the flow sensors indicating either (i) that the flow rate has dropped to zero or close to zero to thus characterize the uterine cavity as non-perforated, or (ii) that the flow rate has not dropped to a predetermined threshold level within a predetermined time interval to thus characterize the uterine cavity as perforated or that there is a failure inocclusion balloon 225 or its deployment so that the cervical canal is not occluded. In one embodiment, the threshold level is 0.05 slpm for characterizing the uterine cavity as non-perforated. In this embodiment, the controller provides a signal indicating a non-perforated uterine cavity if the flow drops below 0.05 slpm between the fifth second of the flow and the flow time-out, which can be, for example, 30 seconds.
• FIG. 14 depicts aspects of an algorithm used bycontroller 410 to accomplish a uterine cavity integrity check, with the first step comprising actuating a footswitch or hand switch. Upon actuation, a timer is initialized for 1 to 5 seconds to determine that afluid source 405 is capable of providing a fluid flow, which can be checked by a pressure sensor between thesource 405 andpressure regulator 422. If no flow is detected, an error signal is provided, such as a visual display signal on the control unit 135 (FIG. 1).
• As can be understood fromFIG. 14, after thefluid source 405 is checked, the controller opens thesupply solenoid valve 450 and a timer is initialized for a 1 to 5 second test interval to insure fluid flows through thesubsystem 420 ofFIG. 13, with either or both aflow meter 440 or a pressure sensor. At the same time asvalve 450 is opened, a timer is initialized for cavity integrity test interval of 30 seconds. Thecontroller 410 monitors theflow meter 440 and provides a signal characterizing the uterine cavity as non-perforated if, at any time after the initial 5 second check interval and before the end of the timed-out period (e.g., the 30 second time-out), the flow rate drops below a threshold minimum rate, in one embodiment, to below 0.05 slpm. If the interval times out after 30 seconds and the flow rate does not drop below this threshold, then a signal is generated that characterizes that the uterine cavity is perforated. This signal also can indicate a failure of theocclusion balloon 225.
• Referring toFIG. 14, in one embodiment, in response or otherwise as a result of the signal that the uterine cavity is not perforated, thecontroller 410 can automatically enable and activate the RF ablation system described above to perform an ablation procedure. Thecontroller 410 can provide a time interval from 1 to 15 seconds to allow CO2 gas to vent from theuterine cavity 302 before activating RF energy delivery. In another embodiment, the endometrial ablation system may include theoptional subsystem 275 for exhausting fluids or gas from the uterine cavity during an ablation treatment (seeFIG. 4 and accompanying text). Thissubsystem 275 can be actuated to exhaust CO2 from theuterine cavity 302 which include openingsolenoid valve 285 shown inFIG.4.
• The system can further include an override to repeat the cavity integrity check, for example, after evaluation and re-deployment of theocclusion balloon 225.
• Although particular embodiments of the present invention have been described above in detail, it will be understood that this description is merely for purposes of illustration and the above description of the invention is not exhaustive. Specific features of the invention are shown in some drawings and not in others, and this is for convenience only and any feature may be combined with another in accordance with the invention. A number of variations and alternatives will be apparent to one having ordinary skills in the art. Such alternatives and variations are intended to be included within the scope of the claims. Particular features that are presented in dependent claims can be combined and fall within the scope of the invention. The invention also encompasses embodiments as if dependent claims were alternatively written in a multiple dependent claim format.

Claims (13)

1. A system (300) for characterizing a patient uterus, comprising:

   a source (140A, 405) of a pressurized flow of a fluid;

   a probe (105) for transcervical introduction into a patient's uterine cavity;

   a lumen (120) mounted to the probe;

   a sensor(440);
   a valve (450) and a pressure regulator (422) for allowing a flow of gas from the source (405) at a predetermined flow rate and pressure to the lumen (120);

   the probe having an elongate introducer member(110 ) for accessing a patient's uterine cavity, the elongate introducer member(110) having a working end (122) ;
   the working end (122) including a flexible, expandable thin-wall member or structure (150) of a dielectric material with a fluid-tight interior chamber (152) that when expanded has a shape extending into substantially all regions of the patient's uterus, and configured for contacting the patient's endometrial lining that is targeted for ablation; and
   a controller (140B;410);

   characterized in that:

   the introducer member (110) comprises a balloon for occluding the cervical canal of the patient.;

   the sensor is a flow sensor for monitoring a change in flow rate of the fluid from the lumen into the uterine cavity;

   the lumen (120) is configured to deliver the fluid from the source to the exterior surfsaces of the expanded dielectric structure (150) to fill the uterine cavity;

   the controller (410) being operatively coupled t the flow sensor (440) and configured to characterize the uterine cavity as at least one of perforated or non-perforated based on the change in the rate..
2. The system of claim 1, wherein the controller generates a signal if the flow does not drop below a predetermined level to thus characterize the uterine cavity as perforated.
3. The system of claim 1, wherein the controller (140B;410) is configured to generate a signal if the flow drops below a predetermined level to thus characterize the uterine cavity as non-perforated.
4. The system of claim 1, wherein the working end (122) comprises an energy-delivery surface for ablating uterine cavity tissue.
5. The system of claim 4, wherein the energy-delivery surface is configured to deliver RF energy to the tissue.
6. The system of claim 4, wherein the energy-delivery surface includes at least one electrode coupled to an RF generator.
7. The system of claim 4, wherein the controller (140B;410) is configured to disable activation of the energy-delivery surface if the uterine cavity is characterized as perforated.
8. The system of claim 7, further comprising an override mechanism to override the disabling mechanism.
9. The system of claim 4, wherein the controller (140B;410) is configured to enable activation of the energy-delivery surface if the uterine cavity is characterized as non-perforated.
10. The system of claim 9, wherein the controller is configured to automatically activate the energy delivery surface if the uterine cavity is characterized as non-perforated.
11. The system of claim 1, wherein the flow sensor is a mass flow sensor.
12. The system of claim 1, wherein the controller is operatively coupled to the source of the pressurized fluid flow, said controller being configured to, 1, initiate a flow of fluid from the fluid source through the lumen into the uterus to the region surrounding the exterior of the fluid-tight wall of the expandable member after the expandable member has been expanded to cause the expandable member to occupy the uterine cavity and before a neutral gas is delivered to an interior of the expandable member to enable ablation, and, 2, measure the flow rate of the flow of fluid into the uterus region surrounding the exterior of the fluid-tight expandable member using the flow sensor, and, 3, determine if the measured flow rate of the fluid flow into the uterus drops below a predetermined minimum threshold rate within a predetermined period of time, wherein the controller generates a signal that the uterus is perforated if the flow rate fails to fall below said predetermined minimum threshold rate within said predetermined time period.
13. The system of any preceding claim, wherein the shape of the thin-wall member or structure is triangular.

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